Automated sum-peak suppression in an X-ray fluorescence analyzer

1. A method of operating an XRF analyzer, comprising:

directing a primary beam of x-ray radiation onto a sample;

detecting radiation emitted from the sample;

constructing an energy spectrum of the detected radiation;

processing the constructed energy spectrum to identify a sum-peak in the energy spectrum that overlaps a characteristic peak of an element of interest, the processing of the constructed energy spectrum including:

calculating a concentration and a limit of detection of the element of interest using information about the identified sum-peak, including deconvoluting the contributions of the interfering sum-peak and the characteristic peak to a measured intensity; and

terminating the analysis when the calculated limit of detection meets a targeted objective;

positioning a filter in the path of the emitted radiation, the filter at least partially inhibiting the passage of radiation of an energy that contributes to the identified sum-peak; and

detecting the filtered radiation, and constructing a filtered spectrum of the detected filtered radiation.

2. The method of claim 1 , wherein the step of positioning a filter further comprises adjusting a parameter of the primary x-ray radiation beam to compensate for attenuation of the radiation of the element of interest by the filter.

3. The method of claim 1 , wherein the step of positioning the filter comprises selecting a filter from a plurality of available filters based on the energy of the radiation that contributes to the sum-peak.

4. The method of claim 1 , wherein the filter is at least partially fabricated of at least one of titanium, vanadium and chromium.

5. The method of claim 1 , wherein the element of interest is lead.

6. The method of claim 1 , further comprising a step of determining a concentration of the element of interest from the filtered energy spectrum.

7. A method of operating an XRF analyzer, comprising:

directing a primary beam of x-ray radiation onto a sample;

constructing an energy spectrum of the detected radiation:

processing the constructed enemy spectrum to identify a sum-peak in the energy spectrum that overlaps a characteristic peak of an element of interest, the processing of the constructed energy spectrum including:

selecting a characteristic peak in the energy spectrum of an element other than the element of interest;

calculating the intensity products of sum-peaks produced by combination of the selected characteristic peak with each of a set of peaks in the energy spectrum, the set of peaks including the selected peak;

comparing the calculated intensity products to a specified threshold; and

determining whether the energy of each of the sum-peaks that exhibits an intensity that meets the specified threshold is within a window of the characteristic peak of the element of interest;

postioning a filter in the path of the emitted radiation, the filter at least partially inhibiting the passage of radiation of an energy that contributes to the identified sum-peak, and

detecting the filtered radiation, and constructing a filtered spectrum of the detected filtered radiation.

8. The method of claim 7 , wherein the step of selecting a characteristic peak includes selecting the characteristic peak having the highest intensity in the energy spectrum.

9. The method of claim 7 , wherein the selecting, calculating, comparing and determining steps are repeated for each of a plurality of characteristic peaks of elements other than the element of interest.

10. An x-ray fluorescence (XRF) analyzer, comprising:

an x-ray source for generating a primary x-ray beam to irradiate a sample;

a detector positioned to receive radiation emitted from the sample and configured to responsively produce pulses representative of the energies of the received radiation;

a programmable controller, coupled to the detector, for accumulating and processing the pulses produced by the detector and constructing an energy spectrum of the radiation emitted from the sample;

a filter apparatus for selectively positioning a filter in the path of the emitted radiation;

wherein the programmable controller is programmed with instructions for performing steps of:

constructing an energy spectrum of the detected radiation,

processing the constructed energy spectrum to identify a sum-peak in the energy spectrum that overlaps a characteristic peak of an element of interest, the processing of the constructed energy spectrum including:

calculating a concentration and a limit of detection of the element of interest using information about the identified sum-peak, including, characteristic peak to a measured intensity; and

terminating the analysis when the calculated limit of detection meets a targeted objective;

causing the filter apparatus to position a filter in the path of the emitted radiation that at least partially inhibits the passage of radiation of an energy that contributes to the identified sum-peak; and

constructing a filtered spectrum of the detected filtered radiation.

11. The XRF analyzer of claim 10 , wherein the filter apparatus comprises a filter wheel having first and second filters mounted therein, the first and second filters differing in at least one of thickness and material.

12. The XRF analyzer of claim 11 , wherein the controller is programmed with instructions for selecting one of the first and second filters based on the energy of the radiation that contributes to the sum-peak.

13. The XRF analyzer of claim 10 , wherein the controller is programmed with instructions to adjust a parameter of the primary x-ray beam to compensate for attenuation of fluoresced radiation of the element of interest by the filter.

14. The XRF analyzer of claim 10 , wherein the programmable controller is programmed with instructions for calculating a concentration and a limit of detection of the element of interest from the energy spectrum using information about the identified sum-peak and terminating the analysis when the calculated limit of detection meets a targeted objective.

15. The XRF analyzer of claim 10 , wherein the programmable controller is programmed with instructions for calculating a concentration of the element of interest based on the filtered energy spectrum.

16. The XRF analyzer of claim 10 , wherein the detector is a silicon drift detector.